In 1997 he was appointed Commanding Officer of the 2nd Battalion, Royal Australian Regiment (2 RAR), holding that position until the end of 1998, when he was posted as the Chief Instructor for the Command, Staff Operations Wing at the Army All Corps Promotion Training Centre in Canungra.[1]

Morrison was promoted to brigadier in November 2002, and commanded the 3rd Brigade from December 2002 until December 2004.[1] He was then appointed as Director-General Preparedness and Plans – Army (DGPP-A) and held that position until his promotion to major general in December 2005.[1]

Morrison took up the appointment of Deputy Chief of Army in February 2008, replacing Major General John Cantwell. He served in this position until December, when he was appointed Land Commander Australia (LCAUST).[1] Following a re-structure in July 2009, the post of Land Commander Australia was re-designated as Commander Forces Command.[1] Morrison was appointed an Officer of the Order of Australia in the Australia Day Honours List of 2010 for distinguished service to the Australian Army in the fields of training and education, military strategic commitments and force structure and capability; in particular, as Commander Australian Defence College, Head Military Strategic Commitments and Deputy Chief of Army.[3]

Morrison was promoted to lieutenant general on 23 June 2011, and assumed the post of Chief of Army in a ceremony the following day.[4] On 4 April 2014, it was announced that Morrison's term as Chief of Army had been extended for twelve months, to June 2015.[5]

In June 2013, Morrison ordered an investigation into several emails sent from Army accounts over a three-year period that were highly demeaning to women. At a 13 June press conference, Morrison announced that he had suspended three members of the Army, ordered action to consider the suspension of five others, and suggested as many as nine more could face disciplinary action. He described the emails as "explicit, derogatory, demeaning and repugnant," and suggested that the alleged conduct was even worse than the "Skype scandal" of 2011.[8][9] In a video posted on the Army's official YouTube channel, a visibly irate Morrison described the alleged behaviour as a "direct contravention" of the Army's values. He added that he had been committed ever since becoming Chief of Army to making the Army an inclusive force. "If that does not suit you," he said, "then get out!" He also told anyone not willing to work with women and accept them as equals, "There is no place for you amongst this band of brothers and sisters."[10]

Morrison's aggressive response was widely hailed by Australian[11][12] and American[13] media, in particular comparing it to the relatively guarded response of the U.S. military to similar accusations.[14]

In June 2014 Morrison formed part of the Australian delegation to the Global Summit To End Sexual Violence in Conflict in London, to which he delivered a speech arguing that armies that separate themselves from civil society, value men over women and celebrate violence "do nothing to distinguish the soldier from the brute".[15]